Image sensing apparatus and storage medium

ABSTRACT

An image sensing apparatus includes an image sensing unit which sequentially generates still image data, a holding unit which holds a plurality of still image data, a display unit which displays the still image data, a setting unit which sets a predetermined state as the start timing of shooting by the image sensing unit, a determination unit which determines whether the predetermined state has been obtained, a shooting control unit which causes the image sensing unit to start shooting when the determination unit determines that the predetermined state has been obtained, a display control unit which causes the display unit to sequentially display, at a display speed lower than an actual time, the still image data, a selection unit which selects one of a plurality of image data displayed on the display unit, and a recording unit which records the selected image data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Divisional of U.S. application Ser. No. 12/481,667, filed Jun.10, 2009 now U.S. Pat. No. 8294779, which is based upon and claims thebenefit of priority from prior Japanese Patent Application No.2008-170421, filed Jun. 30, 2008, the entire contents of both of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image sensing apparatus suited toshooting, for example, a fast-moving object, and a storage medium.

2. Description of the Related Art

There has conventionally been proposed a technique of easily extractinga representative frame which reflects the user intention in movieshooting by a digital camera, as disclosed in patent reference 1: Jpn.Pat. Appln. KOKAI Publication No. 2006-253768. According to thetechnique in patent reference 1, before the user presses a still imagerecording button or when image data shot in successive periods are to becompressed into movie data, the number of I (Intra)-pictures capable ofgenerating a still image independently of preceding and succeedingframes is increased from that in normal movie shooting.

According to this technique, movie data to undergo slow-motion playbackor the like is formed from images shot during a predetermined period (tobe referred to as an “I-picture increasing period” hereinafter) beforethe user presses the still image recording button.

If the user presses the still image recording button with a delay of theI-picture increasing period or more from the timing to shoot image datathe user wants, the generated movie data does not contain the image hewants.

However, user operation often misses the timing to capture movie datathe user wants.

It is an object of the present invention to provide an image sensingapparatus capable of easily adjusting the capturing start timing of aseries of still image data having a limited time width without missingthe shooting timing the user wants even for a quickly moving object, anda storage medium.

BRIEF SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided an imagesensing apparatus comprising: an image sensing unit which shoots anobject image to sequentially generate still image data; a holding unitwhich accumulates and holds a plurality of still image data obtained bythe image sensing unit; a display unit which displays the still imagedata held in the holding unit; a setting unit which sets a predeterminedstate as a start timing of shooting by the image sensing unit; adetermination unit which determines whether the predetermined state setby the setting unit has been obtained; a shooting control unit whichcauses the image sensing unit to start shooting when the determinationunit determines that the predetermined state has been obtained; adisplay control unit which causes the display unit to sequentiallydisplay, at a display speed lower than an actual time, still image dataheld in the holding unit in shooting started by the shooting controlunit; a selection unit which selects one of a plurality of image datadisplayed on the display unit; and a recording unit which records theimage data selected by the selection unit.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIG. 1 is a block diagram showing the schematic arrangement of thefunctional circuit of a digital camera according to an embodiment of thepresent invention;

FIG. 2 is a flowchart showing the contents of shooting processing mainlyin a slow live mode according to the embodiment;

FIG. 3 is a view exemplifying a slow liveview start condition settingdisplay window according to the embodiment;

FIGS. 4A to 4C are views showing a basic sequence to select one stillimage data when “manual” is set as a slow liveview start conditionaccording to the embodiment; and

FIG. 5 is a view exemplifying a display window when “move out” is set asa slow liveview start condition according to the embodiment.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention which is applied to a digitalcamera for shooting a still image will now be described with referenceto the accompanying drawing.

FIG. 1 shows the circuit arrangement of a digital camera 10 according tothe embodiment. Referring to FIG. 1, the optical image of an object isformed via a lens optical system 11 on the image sensing surface of aCCD 12 serving as a solid-state image sensor.

In the monitoring state, an image signal obtained from the image sensedby the CCD 12 is sent to an image processing unit 13. The imageprocessing unit 13 executes correlated double sampling, automatic gaincontrol (AGC), and analog-to-digital conversion to convert the imagesignal into digital image data. Then, the image processing unit 13performs color processes including pixel interpolation and γ correctionfor the digital image data. A buffer memory 14 temporarily holds theprocessed image data.

The image data held in the buffer memory 14 is read out to the imageprocessing unit 13, sent to a display unit 15 via a system bus SB, anddisplayed as a monitor image.

A control unit 16 comprehensively controls all these operations. Thecontrol unit 16 includes a CPU, and is connected to a main memory 17 andprogram memory 18. The main memory 17 is formed from a synchronous DRAM(SDRAM). The program memory 18 is formed from an electrically erasablenonvolatile memory which stores operation programs including a recordingcontrol program in a shooting mode (to be described later), permanentdata, and the like.

The control unit 16 reads out a necessary program, data, and the likefrom the program memory 18, and temporarily stores them in the mainmemory 17 upon expansion. During this, the control unit 16 controls theoverall digital camera 10.

The control unit 16 executes various control operations incorrespondence with a key operation signal directly input from a keyinput unit 19. The control unit 16 is connected via the system bus SB toa lens optical system driving unit 20, flash driving unit 21, CCD driver22, memory card controller 23, built-in memory 24, Universal Serial Bus(USB) interface 25, and audio processing unit 26, in addition to theimage processing unit 13 and display unit 15.

The key input unit 19 includes a power key, shutter button, shootingmode key, playback mode key, menu key, cursor (“↑”, “→”, “↓”, and “←”)keys, set key, scene programming key, camera shake correction key, andface recognition function key.

The lens optical system driving unit 20 receives a control signal fromthe control unit 16 to control the rotation of a lens motor (M) 27. Thelens motor 27 is coupled to some of lenses, e.g., a focusing lens andzoom lens which configure the lens optical system 11. As the lens motor27 rotates, the focusing lens and zoom lens move along the optical axis.

In still image shooting, the flash driving unit 21 receives a controlsignal from the control unit 16 to turn on and drive a flash unit 28 insynchronism with the shooting timing. The flash unit 28 includes aplurality of white high-intensity LEDs.

The memory card controller 23 is connected to a memory card 29 via acard connector C. The memory card 29 is a recording memory for imagedata that is detachably mounted in the digital camera 10 and serves asthe recording medium of the digital camera 10. The memory card 29incorporates a flash memory serving as a nonvolatile memory electricallyerasable for each block, and its driving circuit.

The built-in memory 24 is an image recording memory permanently mountedin the digital camera 10 separately from the detachable memory card 29.The built-in memory 24 similarly includes a flash memory serving as anonvolatile memory electrically erasable for each block, and its drivingcircuit.

When the memory card 29 is not mounted, the built-in memory 24 functionsas the recording medium of the digital camera 10 to record image dataand the like. When the memory card 29 is mounted, it is preferentiallyused.

Image data and the like can be arbitrarily copied and moved between thememory card 29 and the built-in memory 24.

The USB interface 25 controls reception/transmission of data whenconnected to an external device (e.g., personal computer) of the digitalcamera 10 via a USB connector 30.

The audio processing unit 26 includes a sound source circuit such as aPCM sound source. When recording audio data, the audio processing unit26 digitizes an audio signal input from a microphone 31 arranged on thefront surface of the housing of the digital camera 10. The audioprocessing unit 26 compresses the digital data into a predetermined datafile format such as moving picture experts group-4 advanced audio coding(AAC), creating an audio data file. The audio processing unit 26 sendsthe audio data file to the memory card 29 or built-in memory 24.

When playing back audio data, the audio processing unit 26 decompressesan audio data file read out from the memory card 29 or built-in memory24, and converts the decompressed audio data into an analog signal. Theaudio processing unit 26 drives a loudspeaker 32 attached to the rearsurface of the digital camera 10 to amplify the analog signal and outputthe amplified one.

The image processing unit 13 includes an object recognition unit 33 andcompression/decompression processing unit 34.

The object recognition unit 33 executes various kinds of recognitionprocesses for an object in image data. For example, the objectrecognition unit 33 performs face recognition by extracting an edge andface feature points from image data held in the buffer memory 14 tocreate a face graph. Also, the object recognition unit 33 calculates themoving amount between image frames of an object image as a motionvector.

When shooting an image in response to the shutter button operation ofthe key input unit 19, the compression/decompression processing unit 34greatly reduces the data amount of image data to be held in the buffermemory 14 by performing data compression processing such as discretecosine transformation (DCT) or Huffman coding for a predetermined datafile format such as the Joint Photographic Experts Group (JPEG) format.

The memory card 29 or built-in memory 24 records an image data filecreated by the compression/decompression processing unit 34.

In the playback mode, the compression/decompression processing unit 34executes decompression processing to decompress image data read out fromthe memory card 29 or built-in memory 24 in procedures reverse to thosein recording, thereby obtaining image data of an original size. Then,the buffer memory 14 holds the obtained image data. The display unit 15executes playback display based on the image data held in the buffermemory 14.

An operation in the embodiment will be explained.

Any operation in the embodiment is executed when the control unit 16reads out an operation program, permanent data, and the like stored inthe program memory 18 to expand them in the main memory 17. Theoperation program and the like are stored in the program memory 18 inthe manufacture of the digital camera 10, or installed and held in itafter downloading them from an external device connected via the USBinterface 25 and USB connector 30.

In the description of the operation in the embodiment, a shutter button,which is one of the keys of the key input unit 19, is assumed to havetwo operation stokes.

In normal still image shooting, the digital camera 10 performs an autofocus (AF) operation and auto-exposure (AE) operation to lock the focusposition, aperture value, and shutter speed in response to a so-calledhalf-stroke which is an operation stroke of the first stage to press theshutter button halfway with a slight resistance.

Then, the digital camera 10 shoots a still image in response to aso-called full stroke which is an operation stroke of the second stageto press the shutter button to the bottom without temporarily cancelingthe shutter button operation from the half-stroke. The memory card 29 orbuilt-in memory 24 records the shot image data.

The following operation example is directed not to the normal stillimage shooting but mainly to a shooting operation called slow liveshooting.

In slow live shooting, a plurality of still image data are shotcontinuously to hold a series of continuously shot images in the buffermemory 14. The display unit 15 sequentially displays the still imagedata held in the buffer memory 14 at a speed much lower than theshooting speed. When the user selects one image in accordance with thedisplay timing, the memory card 29 records only the selected still imagedata.

The number of continuously shootable still image data is determined bythe capacity of the buffer memory 14, and an image size and imagequality set at that time. The user can arbitrarily set a continuousshooting speed for a series of images within a predetermined range asthe frame rate such as 60 frames/second.

FIG. 2 shows the processing contents of slow live shooting. The controlunit 16 executes this processing by expanding, in the main memory 17, anoperation program read out from the program memory 18.

At the beginning of the processing, the control unit 16 starts pastshooting to cyclically store continuously shot image data of apredetermined past time (e.g., 1 second) in the buffer memory 14regardless of the shutter button operation of the key input unit 19(step S101).

At the start of past shooting, new still image data are written in thebuffer memory 14. At the same time, the oldest still image data iserased. This operation is repetitively executed to always storecontinuously shot images of immediately past 1 second.

At the start of past shooting, the display unit 15 starts normalliveview display to display in real time the contents of the lateststill image data stored in the buffer memory 14 (step S102).

Based on whether the user has done a predetermined key operation to thekey input unit 19, the control unit 16 determines whether he hasdesignated a shift from the normal liveview display to a slow live mode(step S103). If NO in step S103, the sequence returns to the process instep S102.

The processes in steps S102 and S103 are repetitively executed in theabove-described way during the normal liveview display until the userdesignates a shift to the slow live mode.

If the user designates a shift to the slow live mode by a predeterminedkey operation to the key input unit 19 using a combination of the menukey, cursor (“↑”, “→”, “↓”, and “←”) keys, and set key, the control unit16 detects it in step S103 and starts a continuous AF operation (stepS104).

In the continuous AF operation, the AF operation is executedcontinuously without locking the in-focus position, so as to keep even amoving object in focus.

In the continuous AF operation, the control unit 16 determines whetherthe user has done a key operation to newly select a slow liveview startcondition (step S105).

If the user has not done this key operation, the control unit 16determines whether a preset slow liveview start condition has alreadybeen established (step S110).

If no slow liveview start condition has been established, the sequencereturns again to the process in step S104.

While repetitively executing the processes in steps S104, S105, andS110, the sequence waits until the user performs a key operation tonewly select a slow liveview start condition or the slow liveview startcondition is established.

If the user performs a key operation to newly select a slow liveviewstart condition, the control unit 16 detects it in step S105, and thesequence shifts to a process to select a slow liveview start condition(step S106).

FIG. 3 exemplifies a slow liveview start condition selection windowdisplayed on the display unit 15. In FIG. 3, a plurality of conditionsare prepared in advance, including “manual”, “move in”, “move out”,“object stops”, “object smiles”, “person's face appears”, and “panning”.

“Manual” starts the slow liveview when the user presses the shutterbutton halfway.

FIGS. 4A to 4C show a basic sequence to select one still image data when“manual” is set as the slow liveview start condition. The CCD 12 isassumed to have sensed a series of images, as represented in FIG. 4A. InFIG. 4A, “n−2”, “n−1”, . . . , and “n+7” represent the frame numbers ofimage frames.

If the user presses the shutter button halfway at a timing Ths when theimage frame “n−1” is shot, the buffer memory 14 temporarily stores, ascontinuously shot images, image data of a predetermined number of framesstarting from that of the image frame “n” immediately after the imageframe “n−1.

For descriptive convenience, the buffer memory 14 stores image data of atotal of six frames up to the image frame “n+5”. In practice, when theframe rate is 30 frames/second, the buffer memory 14 stores image dataof 30 frames, i.e., 1 second.

Simultaneously when the buffer memory 14 stores image data of apredetermined number of frames, image data are read out from the buffermemory 14 at a frame rate of, e.g., 1 frames/second much slower than anactual time, and sequentially displayed on the display unit 15.

In FIG. 4B, temporally successive image data of six frames arecyclically displayed as indicated by an arrow IV.

While cyclically displaying continuously shot images of a predeterminednumber of frames, i.e., a predetermined time to allow the user tovisually recognize the contents of each image, the sequence waits untilhe presses the shutter button fully subsequently to the half-stroke ofthe shutter button.

In FIG. 4B, the user presses the shutter button fully at a timing Thfwhen the image frame “n+2” is displayed. The control unit 16 determinesthat the user has selected still image data he wants by the full strokeof the shutter button. Then, the compression/decompression processingunit 34 compresses only the still image data of the image frame “n+2”,as represented in FIG. 4C. The memory card 29 or built-in memory 24records the compressed still image data.

In the basic operation of FIGS. 4A to 4C, when the slow liveview startsin response to the half-stroke of the shutter button, still image dataof the image frame “n” immediately after the timing Ths is positioned atthe start of a series of continuously shot image data. In theembodiment, as described in step S101, the past shooting function runsto always store continuously shot images of a predetermined time in thebuffer memory 14.

For this reason, the buffer memory 14 stores images of a total of 2seconds, i.e., 1 second before the timing Ths when the shutter buttonwas pressed halfway and 1 second after it. The slow liveview displayalso starts sequentially from image data of 1 second before the timingThs when the shutter button was pressed halfway.

Referring back to FIG. 3, “(auto)” is added to the starts of the itemnames of the remaining start conditions “move in”, “move out”, “objectstops”, “object smiles”, “person's face appears”, and “panning”. As isapparent from “(auto)”, these conditions are set to automatically startthe slow liveview upon a temporal change of an object in still imagedata obtained by shooting regardless of a key operation by the user.

The conditions “move in” and “move out” are to detect the contact of anobject with a virtual frame in a monitor image displayed on the displayunit 15 when the object externally moves in the frame or internallymoves out of it. Upon the detection, the slow liveview starts.

FIG. 5 exemplifies a monitor image on the display unit 15 at the “moveout” setting. A rectangular frame FR is displayed slightly leftward fromthe center of the display unit 15. The rectangular frame FR contains abird (eagle) as an object OJ. For example, when the object OJ moves andcomes into contact with the rectangular frame FR on the display unit 15,the slow liveview starts automatically.

The condition “an object stops” is to calculate the motion vectorbetween temporally adjacent image frames. When the total motion vectorof the entire image becomes less than or equal to a predetermined value,it is determined that the object stops, and the slow liveview startsautomatically.

The condition “an object smiles” is to perform face recognitionprocessing for image data using the object recognition unit 33, therebyextracting a person's face and analyzing the facial expression. When theanalysis result exceeds a preset index to determine that the expressionis a smile, the slow liveview starts automatically.

The condition “person's face appears” is to perform face recognitionprocessing for image data using the object recognition unit 33. When aperson's face, which has not been extracted before, is extracted, theslow liveview starts automatically.

The condition “panning” is to calculate the motion vector betweentemporally adjacent image frames at, e.g., each of the center andperiphery of image data. When the magnitude of the motion vector at theperiphery exceeds a preset index much more than that of the motionvector at the center, the slow liveview starts automatically.

If the slow liveview start condition selection processing ends in stepS106 of FIG. 2, the control unit 16 determines whether the selectedstart condition is either “move in” or “move out” (step S107).

Only when the control unit 16 determines that the selected startcondition is “move in” or “move out”, the size and position of the frameFR displayed on the display unit 15 are adjusted (step S108).

After that, the control unit 16 sets all the selected slow liveviewstart condition, the adjustment contents of the frame FR especially forthe start condition “move in” or “move out”, and the like (step S109).

The sequence advances to step S110 to determine whether the newly setslow liveview start condition has been established. If no slow liveviewstart condition has been established, the sequence returns again to theprocess in step S104.

The processes in steps S104, S105, and S110 are repetitively executed.The sequence waits until the user performs a key operation to newlyselect a slow liveview start condition or the slow liveview startcondition is established. If the set slow liveview start condition isestablished, the control unit 16 detects it in step S110.

In this case, the control unit 16 determines whether the set slowliveview start condition is “manual”, “move in”, or “move out” (stepS111).

If the control unit 16 determines that the set start condition is“manual”, “move in”, or “move out”, it calculates the object movingspeed as the magnitude (number of pixels) of a motion vector betweencurrent image data and image data which has been shot immediately beforethe current image data and is stored in the buffer memory 14 (stepS112).

That is, when the control unit 16 determines that the set startcondition is “manual”, it calculates the object moving speed bycomparing an image frame obtained when the user pressed the shutterbutton halfway, and an image frame shot immediately before it.

When the control unit 16 determines that the set start condition is“move in” or “move out”, it calculates the object moving speed bycomparing an image frame shot when the contact of the object with theframe was detected, and an image frame shot immediately before it.

The control unit 16 sets the slow liveview speed, e.g., the display timeper image frame from the calculated object moving speed (step S113).

This calculation uses preset moving speed thresholds PX1 and PX2(PX1<PX2). When an object moving speed PXn is lower than the thresholdPX1, it is determined that the object moves slowly (=moving distance inimage data is short [number of pixels is small]. Thus, the slow liveviewspeed is set as high as, e.g., 0.5 seconds per image frame.

When the object moving speed PXn is greater than or equal to thethreshold PX1 and lower than the threshold PX2, it is determined thatthe object moves at a normal speed, and the slow liveview speed is setto a normal speed of, e.g., 1 second per image frame.

When the object moving speed PXn is greater than or equal to thethreshold PX2, it is determined that the object moves quickly (=movingdistance in image data is long [number of pixels is large]. Hence, theslow liveview speed is set as low as, e.g., 2 sec per image frame.

Then, the slow liveview starts using a series of still image data storedin the buffer memory 14. At the set speed, the display unit 15cyclically displays still image data of a total of 2 seconds, i.e., 1second before the timing when the start condition was established and 1second after it (step S114).

At this time, the display unit 15 provides on screen display (OSD) of aguide message such as “Cancel→Menu/select→Full Stroke of Shutter” TheOSD prompts the user to perform a key operation to select or cancel animage.

While executing the slow liveview display, the control unit 16determines whether the user has done a cancel key operation using thekey input unit 19 (step S115).

If the user has not performed the cancel key operation, the control unit16 determines whether the user has pressed the shutter button fully toselect an image (step S116).

If the user has not pressed the shutter button fully to select an image,either, the sequence returns to step S114.

While repetitively executing the processes in steps S114 to S116 topresent the slow liveview display, the sequence waits until the userperforms a key operation to cancel or select an image.

If the user performs a cancel key operation during the slow liveviewdisplay, the control unit 16 detects it in step S115, and the sequencereturns again to the processes from step S102 in preparation for thenext shooting.

If the user presses the shutter button fully to select an image duringthe slow liveview display, the control unit 16 detects it in step S116,and selects still image data displayed at this time in the slowliveview. The compression/decompression processing unit 34 compressesthe selected still image data, and the memory card 29 or built-in memory24 records the compressed still image data (step S117). Then, a seriesof slow live shooting operations ends.

As described above, the embodiment can easily adjust the capturing starttiming of a series of still image data having a limited time widthwithout missing the shooting timing the user wants even for a quicklymoving object.

Especially in the embodiment, a temporal change of an object in a seriesof still image data obtained by shooting is detected to start the slowliveview. The embodiment can therefore set a capturing start timingdirectly linked to a still image shooting timing the user wants.

In this case, the slow liveview starts while the object is always infocus by executing the continuous AF operation. This can eliminate an AFtime lag at the start of the slow liveview, achieving a smootheroperation.

As described as “move in” and “move out” in the embodiment, entrance ofan object image into a predetermined area in still image data and exitof an object image from a predetermined area can be set as slow liveviewstart conditions. This allows starting the slow liveview at anappropriate timing even when shooting an object which moves at highspeed so that it is difficult to keep capturing the object in theshooting range.

In slow live shooting, the display speed of the slow liveview iscontrolled in accordance with the object moving speed. A proper displayspeed can be set easily and automatically, and the next shooting can beprepared for quickly.

Since the stop of an object image can be set as a slow liveview startcondition, even an object whose motion is hardly predicted can be easilycoped with.

Further, a combination of face recognition and expression detection ofan object, which have become fully practical these days, can be set as aslow liveview start condition. When the user wants to shoot the smile ofa specific person, a still image he wants can be reliably capturedthough the apparatus automatically selects the shooting timing.

The appearance of a person's face in the shooting range can be set as aslow liveview start condition. Even an object whose motion is hardlypredicted can be easily coped with, canceling an operation delay whenthe object suddenly enters the shooting range.

In addition, the embodiment executes past shooting to capture even stillimages of a predetermined time immediately before the start of the slowliveview. Even if the slow live shooting start timing delays, an imagethe user wants can be shot without missing the desired timing.

In the embodiment, a temporal change of an object in a series of stillimage data obtained by shooting is detected to start the slow liveview.However, the present invention is not exclusive to this. For example, itcan also be set as a predetermined state a case in which a temporalchange of an acoustic characteristic of a sound acquired using themicrophone 31 and audio processing unit 26, e.g., a relative soundpressure has reached a predetermined threshold, or a case in which avoice of a predetermined frequency band such as one or a plurality ofbands is detected.

For example, a pistol sound at the start of a footrace is set as a slowlive shooting start timing. In this way, the present invention isapplied to a wider range of purposes.

In the embodiment, the present invention is applied to a digital camera.However, the present invention is not limited to this, and is alsoapplicable to a video movie camera capable of shooting a still image, acell phone having a camera function, a personal digital assistant (PDA),or a compact electronic device such as a mobile personal computerequipped with a web camera.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. An image sensing apparatus comprising: an imagesensing unit; a holding unit configured to hold a plurality of imagedata elements generated sequentially by the image sensing unit; a firstdisplay control unit configured to cause a display unit to sequentiallydisplay the image data elements held by the holding unit; a motion speeddetecting unit configured to detect a motion speed of a subject in theimage data elements generated sequentially by the image sensing unit; adetection starting unit configured to cause the motion speed detectingunit to detect the motion speed of the subject, based on (i) a positionof a predetermined area in the image data elements displayed by thedisplay unit and (ii) a position of the subject; a setting unitconfigured to set a display speed at which the display unit sequentiallydisplays the image data elements to be slower than an image sensingspeed of the image sensing unit, based on the motion speed detected bythe motion speed detecting unit; and a second display control unitconfigured to cause the display unit to sequentially display the imagedata elements at the display speed set by the setting unit.
 2. Theapparatus of claim 1, wherein the setting unit sets the display speedcorresponding to the motion speed detected by the motion speed detectingunit, based on a plurality of display speeds.
 3. The apparatus of claim1, wherein: the detection starting unit comprises a contact detectingunit configured to detect a contact of the subject with thepredetermined area in the image data elements displayed by the displayunit; and the detection starting unit causes the motion speed detectingunit to start the detection of the motion speed of the subject when thecontact of the subject is detected by the contact detecting unit.
 4. Theapparatus of claim 1, wherein: the detection starting unit comprises anentry detecting unit configured to detect an entry of the subject intothe predetermined area in the image data elements displayed by thedisplay unit; and the detection starting unit causes the motion speeddetecting unit to start the detection of the motion speed of the subjectwhen the entry of the subject is detected by the entry detecting unit.5. The apparatus of claim 1, wherein: the detection starting unitcomprises an exit detecting unit configured to detect an exit of thesubject from the predetermined area in the image data elements displayedby the display unit; and the detection starting unit causes the motionspeed detecting unit to start the detection of the motion speed of thesubject when the exit of the subject is detected by the exit detectingunit.
 6. The apparatus of claim 1, further comprising: an operationdetecting unit configured to detect an external operation when the imagedata elements are sequentially displayed on the display unit at thedisplay speed set by the setting unit; and a recording control unitconfigured to cause a recording unit to record the image data elementsdisplayed by the display unit when the external operation is detected bythe operation detecting unit.
 7. The apparatus of claim 1, wherein: theholding unit cyclically holds the plurality of image data elementsgenerated by the image sensing unit, in an area of the holding unit, fora first period; and the apparatus further comprises a holding controlunit to control the holding unit to continue holding the plurality ofimage data elements generated by the image sensing unit, in a remainingarea of the holding unit, together with the plurality of image dataelements held for the first period in the area of the holding unit, whenthe motion speed detecting unit starts detecting the motion speed of thesubject.
 8. The apparatus of claim 1, further comprising a focusing unitconfigured to adjust a focus on the subject in the image data elementssequentially generated by the image sensing unit.
 9. An image displayapparatus comprising: a holding unit configured to hold a plurality ofimage data elements generated sequentially by an image sensing unit; afirst display control unit configured to cause a display unit tosequentially display the image data elements held by the holding unit; amotion speed detecting unit configured to detect a motion speed of asubject in the image data elements generated sequentially by the imagesensing unit; a detection starting unit configured to cause the motionspeed detecting unit to detect the motion speed of the subject, based on(i) a position of a predetermined area in the image data elementsdisplayed by the display unit and (ii) a position of the subject; asetting unit configured to set a display speed at which the display unitsequentially displays the image data elements to be slower than an imagesensing speed of the image sensing unit, based on the motion speeddetected by the motion speed detecting unit; and a second displaycontrol unit configured to cause the display unit to sequentiallydisplay the image data elements at the display speed set by the settingunit.
 10. An image displaying method comprising: holding a plurality ofimage data elements generated sequentially by an image sensing unit;causing a display unit to sequentially display the held image dataelements; detecting a motion speed of a subject in the image dataelements generated sequentially by the image sensing unit; causingdetection of the motion speed of the subject to be started, based on (i)a position of a predetermined area in the image data elements displayedby the display unit and (ii) a position of the subject; setting adisplay speed at which the display unit sequentially displays the imagedata elements to be slower than an image sensing speed of the imagesensing unit, based on the detected motion speed; and causing thedisplay unit to sequentially display the image data elements at the setdisplay speed.
 11. A non-transitory computer readable recording mediumhaving a program recorded thereon which causes a computer to function asunits comprising: a holding unit configured to hold a plurality of imagedata elements generated sequentially by an image sensing unit; a firstdisplay control unit configured to cause a display unit to sequentiallydisplay the image data elements held by the holding unit; a motion speeddetecting unit configured to detect a motion speed of a subject in theimage data elements generated sequentially by the image sensing unit; adetection starting unit configured to cause the motion speed detectingunit to detect the motion speed of the subject, based on (i) a positionof a predetermined area in the image data elements displayed by thedisplay unit and (ii) a position of the subject; a setting unitconfigured to set a display speed at which the display unit sequentiallydisplays the image data elements to be slower than an image sensingspeed of the image sensing unit, based on the motion speed detected bythe motion speed detecting unit; and a second display control unitconfigured to cause the display unit to sequentially display the imagedata elements at the display speed set by the setting unit.